US4089550A - Rotary gas seal - Google Patents

Rotary gas seal Download PDF

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Publication number
US4089550A
US4089550A US05/752,353 US75235376A US4089550A US 4089550 A US4089550 A US 4089550A US 75235376 A US75235376 A US 75235376A US 4089550 A US4089550 A US 4089550A
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US
United States
Prior art keywords
seal
pipe
gas
rotary
seal member
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US05/752,353
Inventor
Norman Denton
Andrew Baxter Harding
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
STC PLC
Original Assignee
International Standard Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
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Publication of US4089550A publication Critical patent/US4089550A/en
Assigned to STC PLC reassignment STC PLC ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: INTERNATIONAL STANDARD ELECTRIC CORPORATION, A DE CORP.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/018—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
    • C03B37/01884—Means for supporting, rotating and translating tubes or rods being formed, e.g. lathes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L27/00—Adjustable joints, Joints allowing movement
    • F16L27/08—Adjustable joints, Joints allowing movement allowing adjustment or movement only about the axis of one pipe
    • F16L27/0804—Adjustable joints, Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another
    • F16L27/0808—Adjustable joints, Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another the joint elements extending coaxially for some distance from their point of separation
    • F16L27/0812—Adjustable joints, Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another the joint elements extending coaxially for some distance from their point of separation with slide bearings
    • F16L27/0816—Adjustable joints, Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another the joint elements extending coaxially for some distance from their point of separation with slide bearings having radial sealing

Definitions

  • This invention relates to rotary gas seals for providing a gas-tight connection between a pair of pipes having a common axis wherein one pipe is capable of rotation with respect to the other about their common axis.
  • the invention finds particular application in the design of rotary gas seals for use with corrosive gases and vapours such as may be used in chemical vapour reactions used to deposit glass upon the bore of a glass tube.
  • a rotary gas seal for providing a gas-tight connection between a pair of pipes having a common axis wherein one pipe is capable of rotation with respect to the other about their common axis, wherein one of the two pipes extends into the interior of a tubular seal member through an end wall thereof to which it is secured by a rigid gas-tight seal, while the other pipe is rotatably sealed to the seal member in the neighborhood of the other end of the seal member by a gas-tight gland, and wherein the seal member is secured in one part of a rotary bearing so that the bearing axis lies on the common axis of the pipes while said other pipe is secured to the other part of the bearing.
  • FIG. 1 is a sectional view of the rotary seal of this invention.
  • the rotary seal of FIG. 1 is designed for use in the manufacture of glass optical fibre by a process involving the deposition by a chemical vapour oxidation reaction of glass upon the bore of a glass tube, typically made of fused silica.
  • a chemical vapour oxidation reaction of glass upon the bore of a glass tube, typically made of fused silica.
  • the bore of the coated tube is collapsed and the structure is drawn into fibre.
  • the light guiding structure of the completed fibre is provided by or contained in the material deposited by the chemical vapour reaction. It will be apparent that in order to achieve low loss optical fibre it is essential to keep contamination of the deposit to a minimum.
  • the glass tube is continuously rotated during the deposition process, and hence it is necessary to provide a rotary seal between this tube, or a pipe rigidly connected to the tube, and a feed pipe delivering the gases and vapours necessary for the vapour reaction.
  • Leakage at this seal is highly undesirable: leakage into the atmosphere, because the reagents tend to corrode; leakage from the atmosphere, because this is liable to contaminate the reagents.
  • One particular contaminant that leakage from the atmosphere is liable to introduce is hydrogen or hydrogen containing compounds. These are undesirable because they are liable to result in the incorporation of --OH groups into the deposit which produce a number of optical absorption bands, and can lead to the formation of bubbles.
  • a construction of rotary seal in which the reagents can only come into contact with parts made either of glass or of a fluorinated polymer such as polytetrafluoroethylene.
  • One of these parts must be some form of gland where one part slides over another.
  • This gland is preferably made of a fluoroelastomer such as that sold under the Trade Mark VITON.
  • this gland could form the sole bearing between the two parts of the rotary seal, but it has been found that under these circumstances the two parts tend to produce excessive wear of the gland as a result of not running sufficiently true. The wear gives rise to the generation of swarf which is liable to be entrained in the reagents and produce contamination, and the gland relatively quickly becomes insufficiently gas-tight.
  • a separate bearing at the rotary seal the two parts may be constrained to run true thereby reducing both the leakage and the generation of swarf.
  • the rotary seal efforts a gas-tight connection between a fixed pipe 1 and a rotating pipe 2.
  • the two pipes lie on a common axis, and pipe 2 rotates about this axis.
  • Reagents for the chemical vapour reaction are delivered via the stationary pipe 1 to the rotating pipe 2, which is rigidly fixed to the reaction tube (not shown) in which the deposition reaction takes place.
  • the reaction tube is rotated in the chuck of a lathe (not shown).
  • the reagents consist of a silicon halide vapour such as SiCl 4 entrained in dry oxygen.
  • small quantities of halide vapours of other elements, such as germanium to produce a doped silica as the reaction product.
  • these additives are also entrained in oxygen.
  • Pipe 2 is secured with a rigid demountable compression seal through the end wall of a tubular seal member 3 made of polytetrafluoroethylene.
  • a polytetrafluoroethylene ferrule 4 is urged into a co-operating orifice in the end wall of the said member by a threaded nut 5.
  • the nut may be locked against rotation with the aid of a grub-screw 6.
  • a slot 7 is provided in the nut to reduce the risk that tightening of the grub-screw will disturb the seating of the ferrule 4.
  • the nut may be locked in position with a split clamp arrangement.
  • Pipes 1 and 2 are preferably made of polytetrafluoroethylene though alternatively they may be made of glass. In the case of pipe 1 a reason for preferring polytetrafluoroethylene is that the coefficient of friction between the fluoroelastomer and polytetrafluoroethylene is lower than that between the fluoroelastomer and glass.
  • the pipe 1 extends into the seal member well beyond the inner O-ring and terminates just short of the end wall.
  • the pipe 2 extends well into pipe 1 so that in this way a labyrinth is provided for swarf from the O-rings to travel before it can become entrained in the main gas flow.
  • the seal member 3 fits through the central aperture of the inner race 10 of a rigid anti friction bearing which is clamped between a flange 11 on the seal member and a threaded nut 12 engaged over a threaded portion 13 of the seal member.
  • the inner race 10 is supported on balls 14 in an outer race 15.
  • the outer race is a press fit in a housing 16.
  • Three rods 17 secured in this housing 16 carry a plate 18 having a central aperture through which the pipe 1 is a push fit.
  • the pipe is secured through this aperture by a split clamp arrangement forming part of a boss 19 protruding from the plate 18.
  • the aperture in the plate 18 is aligned to lie on the axis of the bearing so that pipe 1 is held on axis by this plate while pipe 2 is held on axis by the seal member 3.
  • the housing 16 is secured by three rods 20 to a fixed part of the lathe (not shown) used to rotate the reaction tube.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Mechanical Engineering (AREA)
  • Joints Allowing Movement (AREA)
  • Sealing Using Fluids, Sealing Without Contact, And Removal Of Oil (AREA)

Abstract

A rotary gas seal provides a gas tight connection between a pair of pipes having a common axis wherein one pipe is capable of rotation with respect to the other about their common axis. One of the pipes extends into the interior of a tubular seal member through an end wall to which it is secured by a rigid gas tight seal. The other pipe is rotatably sealed to the seal member by a gas tight gland. The seal member is secured in one part of a rotary bearing so that the bearing axis lies on the common axis of the pipes while the other pipe is secured to another part of the bearing.

Description

BACKGROUND OF THE INVENTION
This invention relates to rotary gas seals for providing a gas-tight connection between a pair of pipes having a common axis wherein one pipe is capable of rotation with respect to the other about their common axis. The invention finds particular application in the design of rotary gas seals for use with corrosive gases and vapours such as may be used in chemical vapour reactions used to deposit glass upon the bore of a glass tube.
SUMMARY OF THE INVENTION
According to the present invention there is provided a rotary gas seal for providing a gas-tight connection between a pair of pipes having a common axis wherein one pipe is capable of rotation with respect to the other about their common axis, wherein one of the two pipes extends into the interior of a tubular seal member through an end wall thereof to which it is secured by a rigid gas-tight seal, while the other pipe is rotatably sealed to the seal member in the neighborhood of the other end of the seal member by a gas-tight gland, and wherein the seal member is secured in one part of a rotary bearing so that the bearing axis lies on the common axis of the pipes while said other pipe is secured to the other part of the bearing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a sectional view of the rotary seal of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The rotary seal of FIG. 1 is designed for use in the manufacture of glass optical fibre by a process involving the deposition by a chemical vapour oxidation reaction of glass upon the bore of a glass tube, typically made of fused silica. When the deposition has been completed the bore of the coated tube is collapsed and the structure is drawn into fibre. The light guiding structure of the completed fibre is provided by or contained in the material deposited by the chemical vapour reaction. It will be apparent that in order to achieve low loss optical fibre it is essential to keep contamination of the deposit to a minimum.
The glass tube is continuously rotated during the deposition process, and hence it is necessary to provide a rotary seal between this tube, or a pipe rigidly connected to the tube, and a feed pipe delivering the gases and vapours necessary for the vapour reaction. Leakage at this seal is highly undesirable: leakage into the atmosphere, because the reagents tend to corrode; leakage from the atmosphere, because this is liable to contaminate the reagents. One particular contaminant that leakage from the atmosphere is liable to introduce is hydrogen or hydrogen containing compounds. These are undesirable because they are liable to result in the incorporation of --OH groups into the deposit which produce a number of optical absorption bands, and can lead to the formation of bubbles.
For these reasons it is preferred to use a construction of rotary seal in which the reagents can only come into contact with parts made either of glass or of a fluorinated polymer such as polytetrafluoroethylene. One of these parts must be some form of gland where one part slides over another. This gland is preferably made of a fluoroelastomer such as that sold under the Trade Mark VITON. In principle this gland could form the sole bearing between the two parts of the rotary seal, but it has been found that under these circumstances the two parts tend to produce excessive wear of the gland as a result of not running sufficiently true. The wear gives rise to the generation of swarf which is liable to be entrained in the reagents and produce contamination, and the gland relatively quickly becomes insufficiently gas-tight. By the use of a separate bearing at the rotary seal the two parts may be constrained to run true thereby reducing both the leakage and the generation of swarf.
Referring now to the accompanying drawing, the rotary seal efforts a gas-tight connection between a fixed pipe 1 and a rotating pipe 2. The two pipes lie on a common axis, and pipe 2 rotates about this axis. Reagents for the chemical vapour reaction are delivered via the stationary pipe 1 to the rotating pipe 2, which is rigidly fixed to the reaction tube (not shown) in which the deposition reaction takes place. The reaction tube is rotated in the chuck of a lathe (not shown). Typically the reagents consist of a silicon halide vapour such as SiCl4 entrained in dry oxygen. To this may be added small quantities of halide vapours of other elements, such as germanium, to produce a doped silica as the reaction product. Typically these additives are also entrained in oxygen.
Pipe 2 is secured with a rigid demountable compression seal through the end wall of a tubular seal member 3 made of polytetrafluoroethylene. In this demountable seal a polytetrafluoroethylene ferrule 4 is urged into a co-operating orifice in the end wall of the said member by a threaded nut 5. Optionally the nut may be locked against rotation with the aid of a grub-screw 6. In this case a slot 7 is provided in the nut to reduce the risk that tightening of the grub-screw will disturb the seating of the ferrule 4. Alternatively the nut may be locked in position with a split clamp arrangement.
Near the other end of the seal member 3 a pair of grooves house a pair of 0-rings 8 made of a fluoroelastomer sold under the Trade Mark VITON. These O-rings 8 act as a gland providing a gas-tight seal between the seal member 3 and pipe 1 which is introduced through their centres. Pipes 1 and 2 are preferably made of polytetrafluoroethylene though alternatively they may be made of glass. In the case of pipe 1 a reason for preferring polytetrafluoroethylene is that the coefficient of friction between the fluoroelastomer and polytetrafluoroethylene is lower than that between the fluoroelastomer and glass.
The pipe 1 extends into the seal member well beyond the inner O-ring and terminates just short of the end wall. The pipe 2 extends well into pipe 1 so that in this way a labyrinth is provided for swarf from the O-rings to travel before it can become entrained in the main gas flow.
The seal member 3 fits through the central aperture of the inner race 10 of a rigid anti friction bearing which is clamped between a flange 11 on the seal member and a threaded nut 12 engaged over a threaded portion 13 of the seal member. The inner race 10 is supported on balls 14 in an outer race 15. The outer race is a press fit in a housing 16. Three rods 17 secured in this housing 16 carry a plate 18 having a central aperture through which the pipe 1 is a push fit. The pipe is secured through this aperture by a split clamp arrangement forming part of a boss 19 protruding from the plate 18. The aperture in the plate 18 is aligned to lie on the axis of the bearing so that pipe 1 is held on axis by this plate while pipe 2 is held on axis by the seal member 3. Optionally the housing 16 is secured by three rods 20 to a fixed part of the lathe (not shown) used to rotate the reaction tube.
It is to be understood that the foregoing description of specific examples of this invention is made by way of example only and is not to be considered as a limitation on its scope.

Claims (8)

What is claimed is:
1. A rotary gas seal for providing a gas-tight connection between first and second pipes having a common axis wherein one pipe is capable of rotation with respect to the other about their common axis, comprising:
a tubular seal member having an end wall with an aperture therein, said first and second pipes extending into said tubular seal member from opposite directions;
a rotary bearing having first and second annular portions, said first annular portion rigidly coupled to said second pipe for securing said second pipe, and said second annular portion rigidly coupled to said tubular seal member to provide rotation to said tubular seal member;
a rigid gas-tight seal in said aperture for securing said first pipe; to said tubular seal member and
a gas-tight gland coupled between said tubular sealing member and said second pipe.
2. A rotary gas seal as claimed in claim 1 wherein said first pipe extends into said second pipe so as to form a labyrinth impeding the entrainment of swarf from the gland into gas flowing from either pipe to the other.
3. A rotary gas seal as claimed in claim 1 wherein the gas tight gland is provided by one or more O-rings.
4. A rotary gas seal as claimed in claim 3 wherein the O-ring or rings are made of a fluoroelastomer.
5. A rotary gas seal as claimed in claim 1 wherein the seal member is made of polytetrafluoroethylene.
6. A rotary gas seal as claimed in claim 1 wherein the two pipes are made of polytetrafluoroethylene.
7. A rotary gas seal as claimed in claim 1 wherein said first pipe is secured through the end wall of the seal with a demountable compression seal.
8. A rotary gas seal as claimed in claim 1 wherein the rotary bearing is a rigid ball or roller bearing.
US05/752,353 1976-03-18 1976-12-20 Rotary gas seal Expired - Lifetime US4089550A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB10926/76A GB1529756A (en) 1976-03-18 1976-03-18 Rotary gas seal
UK10926/76 1976-03-18

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2501668A1 (en) * 1981-03-11 1982-09-17 Western Electric Co METHOD AND DEVICE FOR INTRODUCING A CURRENT OF A FLUID INTO A ROTATING TUBE
FR2504230A1 (en) * 1981-04-21 1982-10-22 Lignes Telegraph Telephon ROTATING SEALING DEVICE AND DEVICE FOR MANUFACTURING OPTICAL FIBERS COMPRISING SUCH A SEALING DEVICE
US20100247292A1 (en) * 2009-03-30 2010-09-30 General Electric Company System and Method of Cooling Turbine Airfoils with Sequestered Carbon Dioxide
CN106430941A (en) * 2016-09-09 2017-02-22 长飞光纤光缆股份有限公司 HEC furnace water-cooled gaseous ring device for producing optical fibers
US9627953B1 (en) * 2013-07-21 2017-04-18 Krishendu Das Gupta Buoyancy turbine
CN109824263A (en) * 2019-03-04 2019-05-31 武汉光盛通设备咨询有限公司 The rotary sealing appts of legal system stick equipment in a kind of pipe

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1797382A (en) * 1928-08-03 1931-03-24 Fairmont Box Company Revoluble pipe joint
US1931706A (en) * 1931-06-23 1933-10-24 Francis C Powell Liquid seal for impeller shafts of centrifugal and rotary pumps
US2088418A (en) * 1929-01-15 1937-07-27 Walter E King Hydraulic swivel
GB728431A (en) * 1949-08-16 1955-04-20 William Murray Improvements in and relating to unions for connecting pipes and the like to a rotarymember
US3129960A (en) * 1959-10-01 1964-04-21 Reimers Getriebe Kg Device for feeding pressure fluids from a stationary bearing cover into the outer end of a rotating shaft

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1797382A (en) * 1928-08-03 1931-03-24 Fairmont Box Company Revoluble pipe joint
US2088418A (en) * 1929-01-15 1937-07-27 Walter E King Hydraulic swivel
US1931706A (en) * 1931-06-23 1933-10-24 Francis C Powell Liquid seal for impeller shafts of centrifugal and rotary pumps
GB728431A (en) * 1949-08-16 1955-04-20 William Murray Improvements in and relating to unions for connecting pipes and the like to a rotarymember
US3129960A (en) * 1959-10-01 1964-04-21 Reimers Getriebe Kg Device for feeding pressure fluids from a stationary bearing cover into the outer end of a rotating shaft

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2501668A1 (en) * 1981-03-11 1982-09-17 Western Electric Co METHOD AND DEVICE FOR INTRODUCING A CURRENT OF A FLUID INTO A ROTATING TUBE
FR2504230A1 (en) * 1981-04-21 1982-10-22 Lignes Telegraph Telephon ROTATING SEALING DEVICE AND DEVICE FOR MANUFACTURING OPTICAL FIBERS COMPRISING SUCH A SEALING DEVICE
US4512790A (en) * 1981-04-21 1985-04-23 Lignes Telegraphiques & Telephoniques Rotary sealing device
US20100247292A1 (en) * 2009-03-30 2010-09-30 General Electric Company System and Method of Cooling Turbine Airfoils with Sequestered Carbon Dioxide
CN101936220A (en) * 2009-03-30 2011-01-05 通用电气公司 System and method of cooling turbine airfoils with sequestered carbon dioxide
US8631639B2 (en) * 2009-03-30 2014-01-21 General Electric Company System and method of cooling turbine airfoils with sequestered carbon dioxide
CN101936220B (en) * 2009-03-30 2015-08-26 通用电气公司 With the system and method for carbon dioxide cooled turbine airfoil part
US9627953B1 (en) * 2013-07-21 2017-04-18 Krishendu Das Gupta Buoyancy turbine
CN106430941A (en) * 2016-09-09 2017-02-22 长飞光纤光缆股份有限公司 HEC furnace water-cooled gaseous ring device for producing optical fibers
CN106430941B (en) * 2016-09-09 2019-06-28 长飞光纤光缆股份有限公司 A kind of HEC optical fiber production stove water cooling gas ring device
CN109824263A (en) * 2019-03-04 2019-05-31 武汉光盛通设备咨询有限公司 The rotary sealing appts of legal system stick equipment in a kind of pipe
CN109824263B (en) * 2019-03-04 2024-04-30 武汉光盛通设备咨询有限公司 Rotary sealing device of in-pipe rod making equipment

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Publication number Publication date
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AS Assignment

Owner name: STC PLC, 10 MALTRAVERS STREET, LONDON, WC2R 3HA, E

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:INTERNATIONAL STANDARD ELECTRIC CORPORATION, A DE CORP.;REEL/FRAME:004761/0721

Effective date: 19870423

Owner name: STC PLC,ENGLAND

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:INTERNATIONAL STANDARD ELECTRIC CORPORATION, A DE CORP.;REEL/FRAME:004761/0721

Effective date: 19870423